GB359334A - Improvements in or relating to electrical sound reproducing or recording apparatus - Google Patents

Abstract

359,334. Sound recording and reproducing devices. SOC. FRANCAISE RADIO - ELECTRIQUE, 79, Boulevard Haussmann, Paris. Jan. 26, 1931, No. 2501. Convention date, Feb. 21, 1930. [Class 40 (iv).] Relates to sound recording or reproducing devices, such as phonographic recorders or reproducers or driving units for loud-speakers, in which a permanent magnet is shunted by a member of ferromagnetic material in the central portion of which is located a pivotally mounted armature and consists in pivotally connecting the armature to its support or supports so as to form a straight line contact therebetween and another straight line contact between the armature and yielding means arranged to exert on the armature a force directed transversely to the rocking axis thereof, the lines of contact being coincident with such axis. The figures show a construction of gramophone pick-up comprising a horseshoe magnet 1 provided with polepieces 2 having a recess 3 in the underside thereof in which is located a coil 4. An armature 5 extending through the coil 4 has its lower end formed with a recess 6 to receive a gramophone needle, whilst its upper end is located between pliable stops 8 adjustable by screws 9 extending through the polepieces. A magnetic shunting plate 11 extends across the polepieces, being secured thereto by screws. 20 which also serve to secure a blade spring 19 to the plate 11. The spring 19 extends through a hole 18 in the armature so as to bear on a downwardly directed knife-edge b on a bearing journal A, Figs. 2 and 4, secured in a hole 17 in the armature at right-angles to and intersecting the hole 18. The ends of the journal A which extend beyond the hole 17 are formed with upwardly-directed knife-edges a, c which are pressed into grooves in the plate 11 by the spring 19 acting on the knife-edge b. According to modifications, the direction of the knife-edges may be the reverse of that shown or they may be directed in a horizontal plane. Again, the journal A may be formed with grooves for knife-edges located on the plate 11. This plate may also be formed integral with the polepieces and may be arranged to extend through the hole 18, in which case, the knife-edge b is maintained in contact therewith by springs applied against the knife-edges a, c.